Hard DIsk upgrade on ML370G5

[Northof9]

HP Proliant ML370G5 with P400 controller
Used to have 8 72GB drives in a Raid 1 + 0 or 10 configuration
Total drive space available was 273GB's
Two mirror groups 1-4 and 5-8
C: drive was 48GB and D: was 224GB
Run out of space on C: drive. Even removed page file
Replaced all 72GB drives with 146GB drives in same Raid configuration
Storage space did not go up. Drive container size remained the same
How do I take advantage of the increased drive space?
Do I have to reformat the drives, change the partition size and restore from back up the system?
Need specific steps to follow as this is a mission critical server that HAS to run.
Any input is appreciated.

Thanks